1. Field of the Invention
The present invention relates to a method of controlling an inkjet printer containing at least two substantially closed ducts in which ink is present, comprising:
actuating an electro-mechanical transducer whereby the pressure in a first duct is increased and a pressure change in another duct is also generated by the actuation. The present invention also relates to an inkjet printhead suitable for the use of this method and an inkjet printer provided with such a printhead.
2. Background Art
A method of this kind is known from EP 0 790 126. The known method is used in a printhead for an inkjet printer wherein the printhead comprises a duct plate in which a number of parallel grooves are formed in the longitudinal direction, each groove terminating in an exit opening or nozzle. The duct plate is covered by a flexible plate so that the grooves form a plurality of substantially closed ink ducts. A number of electro-mechanical transducers are provided on the flexible plate at the ducts so that each duct is confronted by one or more of the transducers. The transducers, in this case piezo-electric transducers, are provided with electrodes. When a voltage is applied in the form of an actuation pulse across the electrodes of a piezo-electric transducer of this kind, the result is a sudden deformation of the transducer in the direction of the associated duct, resulting in the pressure in the duct being suddenly increased. As a result, a drop of ink is ejected from the nozzle.
On the side remote from the duct plate, the transducers are supported by a carrier member. The printhead is also provided with a number of connecting elements which connect the carrier member via the flexible plate to the duct plate. These connecting elements serve to increase the mechanical strength of the printhead so that an applied actuation pulse will also always result in the required pressure rise and thus the required drop ejection, i.e. a drop ejection with which the drop, for example, has a previously known size and/or a previously known speed.
The known method, however, has a significant disadvantage. Despite the rugged construction, it is not possible to completely prevent the actuation of a piezo-electric transducer of a first duct from also having an influence on the position in another duct, particularly a neighboring duct. The reason for this is that the actuation causes the piezo-electric transducer to expand, so that mechanical forces are transmitted to the carrier member. Since the carrier member is, in turn, connected to the piezo-electric transducers of the other ducts, these forces will be transmitted to these transducers. This mechanical actuation of these transducers will result in a pressure change in the other ducts, and this pressure change is particularly noticeable in neighboring ink ducts. In many cases, this pressure change increases the closer a neighboring duct is to the duct where the first piezo-electric transducer is electrically actuated. The result of this pressure change is that the drop ejection process in another duct of this kind is adversely influenced. This is also termed cross-talk and may be manifested in a deviant drop size, drop speed, ejection time, and so on. Such deviations will finally result in print artefacts or irregularities, which are visible in varying degrees depending on the nature of the deviation.